Repro 6 and 7 Flashcards
Maternal recognition of pregnancy in Horses caused by:
- not fully understood BUT mobility of embryo is v important
Maternal recognition of pregnancy in primates caused by:
- Gonadotropin
What needs to be STOPPED in order to allow pregnancy?
- Luteolytic signal
- What hormone is essential for pregnancy?
- What secretes it?
3 and 4. Takes a while to secrete so what happens?
- Progesterone
- Placenta secretes
- Takes while before placenta developed sufficiently to secrete enough progesterone sooooo
- Progesterone from corpus luteum can provide progesterone
How do cows and sheep recognise pregnancy?
- The blastocyct produces interferon which blocks synthesis of oxytocin receptors
- This prevents oxytocin releasing PGF from the endometrium
Finding maternal recognition tricky so gover
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Time of placenta attachment in cow sheep mare sow
Most species 21 days, mare later, sow earlier
- cow = 18- 22 days
- Sheep = 15-18 days
- Mare 36- 38 days
- Sow = 11-12
When does most pregnancy loss occur in dairy cattle?
- in first few weeks when maternal recognition of pregnancy and placental attachment is occuring
xxx Describe the form & extent of placental
attachment in the main domestic species
Explain how the extra-embryonic tissues form the
placenta
- What are the three types of embryo tissue
- What form from?
- What do they go on to form
- Endoderm, Mesoderm, Ectoderm (outer)
- form from inner cell mass of blastocyst
- Endoderm = digestive system, lungs, endocrine sysmte
Mesoderm = muscle, skeleton, cardiovascular, reproductive system
Ectoderm = Nervous system, skin, hair
What are the two layers called that protect the embryo and what is inbetween these?
- Embryo, fluid, amnion, fluid, allantochorion
What does embryo develop from from blastocyst?
INNER CELL MASS
Role of placenta
- provides an interface for metabolic exchange between dam and foetus
- Transitional endocrine gland producing hormones to: maintain preg, stimulation of maternal mammary gland, promotrion of foetal growth
What type of placenta do cow and sheep have?
- Cotyledonary placentas = numerous, discrete, button like structures called cotyledons.
- Cow = CONVEX
- Sheep = CONCAVE
What type of placenta do cow and sheep have?
- Cotyledonary placentas = numerous, discrete, button like structures called cotyledons.
- Cow = CONVEX
- Sheep = CONCAVE
Membrane of fetus not attached all way across uterus
What type of placenta do cow and sheep have?
- Cotyledonary placentas = numerous, discrete, button like structures called cotyledons.
- Cow = CONVEX
- Sheep = CONCAVE
Membrane of fetus not attached all way across uterus - 6 layers
What type of placenta pig adn horse
- Diffuse placenta = membranes of foetus attached all way across uterus
- Uniform distribution of chorionic villi
- 6 layers
Placenta of dog and cat
- Zonary placentae
- Band like zone of chorionic villi attachment to mum
- 5 layers
Layers
- outer = atlant coria
- allantoic fluid
- amnia
- amniotic fluid
In early embryo how do gonads develop?
- Primordial cells migrate from yolk sac into gonadal ridge.
- Gonad is bi potential
- local tissue differentiate into sex cords